Dummy load in dc dc converters

[balamanikandan]

hi,

Why dummy load is provided in a DC DC step down Buck converters?

I am looking for the reference design and/or tutorial to understand the design guidelines to include a dummy load. Please share the same with me if any.

 

[mvs sarma]

otherwise, the output would be shown higher after rectification and filtering, even if you have a sensor potential divider as this consists of higher values.

 

[emontllo]

Buck converters do not necessarily need a dummy load whereas other converters may need a minimum load.
The dummy is only needed sometimes for control loop stability reasons or for specific IC specifications.

 

[dick_freebird]

If your current mode control range does not extend to negative
currents, then achieving zero is iffy. A baseline load helps ensure
you are in the linear control range, a fundamental requirement
for deriving a sane loop compensation.

Then, having a finite output impedance (Iout=0, is like infinite and
the load-pole may slide way in and become dominant) helps you
set compensation that has better dynamic response, not having
to accommodate as much range of load-pole movement.

 

[balamanikandan]

hi,

Requirement :

It is necessary for a power supply to retain its normal regulated output voltage in the presence of reverse current flow during part of the operating cycle of an active load device connected to the power supply.

a. Will connecting dummy load in shunt meet the requirement if the buck converter is designed using BJT transistor ?


b. Will connecting dummy load in shunt meet the requirement if the buck converter is designed using MOSFET transistors (Synchronous and Non isloated converter) ?